Conventional heavy-duty vehicle air brake systems use mechanical pneumatic push-pull control valves to actuate and release the vehicle parking brakes and the trailer brake supply line. According to Federal Motor Vehicle Safety Standard (FMVSS) No. 121, the parking brake and the trailer brake controls must be located in close proximity to the driver. This requires the installation of large pneumatic push-pull valves in the vehicle instrument panel and further requires pneumatic lines and connections within the instrument panel, connecting with other components of the truck air brake system. The resulting system is very bulky and uses critical volume in the instrument panel, often imposing design parameters to the detriment of driver comfort and convenience. Furthermore, installation of the instrument panel controls requires making complex airtight connections during final vehicle assembly. With the goal of improving instrument panel design and driver ergonomics, attempts have been made to reduce the volume of switches within the instrument panel. Fundamental limitations, however, limit the potential of this approach. A different approach to controlling application of the parking brake is the use of an electrical switch in the instrument panel, controlling a solenoid driven valve located remotely in the air parking brake system. An inherent disadvantage exists for previous electrically controlled systems. In an air brake system, the braking force is applied by a coil spring whenever the brake line pressure goes below a certain threshold level thus, when the brake line is at atmospheric pressure, the spring, activates the parking brake. In previous electrically controlled systems, when power was lost to the solenoid air valve, the valve would move to the exhaust position, dropping the parking brake line pressure to atmospheric and activating the parking brake. The result could be inadvertent engagement of the parking brake. In conducting a failure mode and effect analysis of such a failure due to a power loss, the combination of a single point failure having significant consequences discourages use of conventional electrical instrument panel controls for vehicle air brake systems of this type.